Why should all guests be respected?
To Hindus a guest is like a god. Serving a guest is like serving God. It is believed that one can offer no greater welcome than to offer hospitality to a guest. The welcome of a guest at the doorstep is not only a responsibility but has been equated with a religious duty.
Religious texts describe the welcome of a guest as atithi yagya. Atithi means guest, and yagya denotes sacrifice or offering. Therefore offering hospitality to a guest is a personal sacrifice or offering. Hospitality to guests is included amongst the responsibilities of a householder. Atithi yagya is one of the five principal yagyas recommended to Hindus. A guest must be entertained and honoured irrespective of caste, status or ability. This kind of hospitality is unique and unknown in other religions.
Maharishi Shatatap has explained that a guest who comes home without a cause, without an invitation, at any time, from anywhere must be considered a god. Whoever is known and comes with an appointment is not a guest.
In the Mahabharata, Udyogparv, 38/2, Mahatma Vidur tells Dhritrashtra:
O King! When a person comes as a guest to one's home a patient man must first offer a seat and then wash his feet with water. Then he must ask about the welfare of the guest and reciprocate according to the situation. Thereafter, depending upon circumstances, a meal must be offered to the guest.